1. Field of the Invention
This invention generally relates to print elements for daisy wheel printers. More specifically, this invention relates to a daisy wheel printer print package including a daisy wheel print element housed in a cartridge for printing and storage.
2. Description of the Prior Art
Representing other work in this same area is U.S. Pat. No. 4,127,335, having Bogert et al. as inventors and entitled "Impact Printer With Cartridge Print Wheel". Disclosed therein are a cartridge and a daisy wheel print element or wheel for use in a daisy wheel printer.
In considering the referenced application in conjunction with the instant application, there are a number of notable similarities. In both applications there are generally disclosed (1) a print element and a cartridge for housing the print element during printing and storage, (2) a leaf spring for acting against a centered bearing projection on the central hub of the print element, (3) a print hammer slot in the upper portion of the front of the cartridge, (4) a centralized opening in the front of the cartridge for accepting a selection motor drive hub and a portion of the central hub, (5) locating and driving means associated with both the print element central hub and drive hub, and (6) the displacement of the print element fromthe front of the cartridge during printing.
Even though these similarities exist, important distinctions are present. To begin with, the cartridge of the instant application substantially encloses the print element to prevent print element damage and soiled hands. In the referenced application, the cartridge does not include a back and a relatively large print hammer slot is provided. Thus, large areas of the print element remain exposed to an operator or other objects. The leaf spring in each application serves the purposes of (1) providing a bearing surface for a print element projection, and (2) urging the print element toward the front of the cartridge. In the instant application though, the leaf spring is structured, located, and oriented to facilitate removal and insertion of the print element with great ease. Also, elaborate mounting apparatus for the leaf spring is eliminated in the instant application. The centralized opening in the front of the cartridge of the referenced application apparently has nothing to do with latching the print wheel in a desired rotational position. In the same light, the print element apparently has no means for insuring its proper orientation within the cartridge.
Representative of yet other work in this same area is U.S. Pat. No. 4,124,312, issued Nov. 7, 1978, to Johnson and entitled "Impact Printer With Print Wheel Cartridge". As was the case with the Bogert et al. patent, Johnson discloses a print element housed in a cartridge. There are also definite similarities between the instant application and Johnson. In fact, Johnson overcomes a deficiency of Bogert et al. in that the print element is substantially enclosed in the cartridge. Important and basic distinctions exist, though. In Johnson, the print element and cartridge are engageable and disengageable, but upon engagement, the print element is not latched against rotation. At best, it is only frictionally held in place upon engagement of the opening in the cartridge and hub on the print element. The hub and opening serve locating and not latching purposes. The print element can still be rotated in place against friction and without any disengagement and unlatching of the print element and cartridge.
Prior art consisting of U.S. Pat. Nos. 3,793,951, 3,805,698, 3,730,602, 4,074,798, Des. 229,427, 3,860,248, 3,797,035, and floppy discs has also been considered relative to this application. A floppy disc is simply a circular magnetic recording medium housed in a folder during recording use and non-use. U.S. Pat. Nos. 3,793,951 and 3,805,698 disclose enclosed chain or belt print elements. U.S. Pat. Nos. 3,860,248, 3,730,602 and Des. 229,427 disclose a cartridge for a magnetic recording disc such as that shown in U.S. Pat. No. 3,797,035. The disc of U.S. Pat. No. 3,797,035 can be stored in one of the cartridges of U.S. Pat. Nos. 3,860,248, 3,730,602, and Des. 229,427 prior to and following recording. U.S. Pat. No. 4,074,798 discloses a daisy wheel print element having substantial central hub structure unassociated with a cartridge. Of the art mentioned in this paragraph, none is considered particularly pertinent. In fact, the majority of this art falls in an area non-analogous to printing.
Other distinctions over the prior art, and the advantages thereof, will become more readily apparent when reference is made to the accompanying drawing and the following description of the preferred embodiment.